brazing a hydraulic line

[sd455dan]

Maybe not the right way but on the spare Rhino tractor I bought this summer, the power steering pressure line had fractured / split for about 1/2" at a low point (thinking water intrusion when it was parked for around 15 years).

I closed up the gap after a good cleaning and flushing then filled the line with Argon /co2 welded it up with regular old .030" ER70S-6 using the HTP MIG. No leaks so far. IIRC it was just a steel line ie. magnetic.

 

[SiteEngineer]

Brazing might hold for a bit, but it’s not a reliable fix for a pressurized hydraulic line. The heat can weaken the metal or make the leak worse later. If it’s at the fitting, the safest move is to replace or reflare that section. It’s pricey, but better than having the line burst under pressure.

 

[TMGT]

Brazing might hold for a bit, but it’s not a reliable fix for a pressurized hydraulic line. The heat can weaken the metal or make the leak worse later. If it’s at the fitting, the safest move is to replace or reflare that section. It’s pricey, but better than having the line burst under pressure.

Silver solder is common practice for attaching hydraulic fittings to tubing. Unless its a flare with a backer, most likely the original fitting with soldered to the tubing.

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[jwmorris]

it's a solid line with fittings on both ends that are welded to the line.

A welded joint that brakes isn't where things like silver solder work very well.

As you are trying to repair a butt type crack vs sweating a slip joint for bond, like this.

For a crack in a welded connection, I'd go over it again with silicon bronze rod and a TIG welder.

Good for sealing and a much stronger joint.

 

[John0829]

You should be ashamed of showing welds that look like that

Beautiful job

 

[coloradotrout]

I need to be able to use a simple Bernzomatic trigger start torch with mapp gas. Also I'm hoping to just remove the fitting from the pump, blow out some fluid, and work on it while the opposite side stays connected to the tractor. Post #22 above has the diagram. It'll be tight quarters.

 

[rScotty]

I use oxy/acetylene because it burns really hot, and have never tried silver soldering with Mapp gas by itself. Mapp gas paired with oxygen would be certainly work. Whatever you use has to heat the tubing, patch, and the silver so that the silver will flow along the tubing and under the patch.

I've heard that straight Mapp gas will work with silver solder only if you are using the lower melting point type of silver solder - which is called "low" or "easy" sillver solder -and forms a brazed bond at about 1400 F. But that should work.

BTW, silver soldering is really a type of brazing. It is not at all like tin alloy plumber's solder which flows at 400 to 600 F. I don't know why "silver brazing" ever got to be called "silver soldering", but it is.

Might as well get some scrap and practice first. It is often easiest to silver braze a patch made of a split piece of similar size tubing onto the hydraulic tubing. You might even try some copper tubing for the patch. Make it fit really well and clean and flux the cleaned metal before brazing it. Or you could get some copper wire and wind it around the tubing and then flow the solder onto that wire. With clean copper, flux, and enough heat the silver should wick along the tube and under the patch and all but disappear. If it flows that nicely, you know the joint is good. The patch helps reinforce the silver. It is easier to patch tubing than to try to just cover a split with solder.

Silver solder rod and flux is kinda expensive.
If you know a refrigeration repair shop, they tend to use a lot of silver solder & might sell you a single rod. Get a lump of their brazing flux, too. You can mix the flux with water if it dries out.

rScotty

 

[coloradotrout]

I use oxy/acetylene because it burns really hot, and have never tried silver soldering with Mapp gas by itself. Mapp gas paired with oxygen would be certainly work. Whatever you use has to heat the tubing, patch, and the silver so that the silver will flow along the tubing and under the patch.

I've heard that straight Mapp gas will work with silver solder only if you are using the lower melting point type of silver solder - which is called "low" or "easy" sillver solder -and forms a brazed bond at about 1400 F. But that should work.

BTW, silver soldering is really a type of brazing. It is not at all like tin alloy plumber's solder which flows at 400 to 600 F. I don't know why "silver brazing" ever got to be called "silver soldering", but it is.

Might as well get some scrap and practice first. It is often easiest to silver braze a patch made of a split piece of similar size tubing onto the hydraulic tubing. You might even try some copper tubing for the patch. Make it fit really well and clean and flux the cleaned metal before brazing it. Or you could get some copper wire and wind it around the tubing and then flow the solder onto that wire. With clean copper, flux, and enough heat the silver should wick along the tube and under the patch and all but disappear. If it flows that nicely, you know the joint is good. The patch helps reinforce the silver. It is easier to patch tubing than to try to just cover a split with solder.

Silver solder rod and flux is kinda expensive.
If you know a refrigeration repair shop, they tend to use a lot of silver solder & might sell you a single rod. Get a lump of their brazing flux, too. You can mix the flux with water if it dries out. I think the leak is right at the line to fitting connection. It's a tiny leak - a drip every 5s.

rScotty

Thank you. The HVAC rod looks to be 15%, whereas the other is 56% or 45%.

 

[TMGT]

Thank you. The HVAC rod looks to be 15%, whereas the other is 56% or 45%.

I used the 56% to make up some hyd. fittings, I used oxy/acetalyne. It definitely takes some heat for it to flow, not sure if the straight mapp is going to do it, depending on the fittings mass.

Do you have a picture of the leaking area? Your initial post made it sound like the joint is leaking rather then a hole in the line. If so a patch is not needed.

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